The present usual practice of fabricating an insulating window sash includes fabricating an insulating glazing unit and mounting sash members around the perimeter and marginal edges of the unit. The insulating unit may be made in any manner, for example, but not limited to the techniques disclosed in U.S. Pat. Nos. 5,655,282; 5,675,944; 5,531,047; 5,617,699 and 5,720,836. The insulating units provide a dead gas space between adjacent sheets.
Although the present usual practice is acceptable, there are limitations. For example, one limitation is making the insulating glazing unit, and thereafter, mounting the sash members around the perimeter of the unit.
As can be appreciated by those skilled in the art of fabricating insulating window sashes, eliminating the manufacturing steps to make an insulating unit significantly reduces the cost of manufacturing the window. Further, it would be advantageous to provide a window sash that has the benefits of an insulating glazing unit without the limitations of mounting sash members around the perimeter of the insulating unit.